Zika Virus Infection and Zika Fever: FAQs

Zika Virus Infection and Zika Fever: FAQs

On Dec. 31, 2015, the National IHR Focal Point (NFP) of the United States of America notified the Pan-American Health Organization (PAHO) and the World Health Organization (WHO) of the first laboratory-confirmed case of Zika virus infection in the Commonwealth of Puerto Rico, an unincorporated territory of the United States. The patient is a resident of Puerto Rico and had no travel history outside the island in the three months prior to the onset of illness. A blood sample obtained from the patient tested positive for Zika viral RNA by reverse transcription polymerase chain reaction (RT-PCR).

Epidemiological investigations are ongoing to determine the source of exposure and detect possible additional cases. Vector control efforts by the Department of Environmental Health, including inspections to identify mosquito breeding sites, is underway. The public is being urged to take preventive measures to avoid mosquito bites.

The PAHO/WHO present the following frequently asked questions (FAQs) about Zika virus infection and Zika fever.

Q: What is Zika virus infection?

A: Zika virus infection is caused by the bite of an infected Aedes mosquito, usually causing mild fever, rash, conjunctivitis and muscle pain. The virus was isolated for the first time in 1947 in the Zika forest in Uganda. Since then, it has remained mainly in Africa, with small and sporadic outbreaks in Asia. In 2007, a major epidemic was reported on the island of Yap (Micronesia), where nearly 75% of the population was infected.

On March 3, 2014, Chile notified PAHO/WHO that it had confirmed a case of indigenous transmission of Zika virus on Easter Island, where the virus continued to be detected until June 2014.

In May 2015, the public health authorities of Brazil confirmed the transmission of Zika virus in the northeast of the country. Since October 2015, other countries and territories of the Americas have reported the presence of the virus. See updated list at: www.paho.org/zikavirus.

Q: What are the symptoms?

A: The most common symptoms of Zika virus infection are mild fever and exanthema, usually accompanied by conjunctivitis, muscle or joint pain, and general malaise that begins 2 to 7 days after the bite of an infected mosquito. 1 out of 4 infected people develops symptoms of the disease.
Among those who do, the disease is usually mild and can last 2-7 days. Symptoms are similar to those of dengue or chikungunya, which are transmitted by the same type of mosquito. Neurological and autoimmune complications are infrequent, but have been described in the outbreaks in Polynesia and, more recently, in Brazil. As the virus spreads in the Americas, giving scientists more experience with its symptoms and complications, it will be possible to characterize the disease better.

Q: How is Zika virus transmitted?

A: Zika virus is transmitted to people through the bite of an infected Aedes mosquito. This is the same mosquito that transmits dengue and chikungunya.

Q: Can it be transmitted through blood or sexual contact?

A: In general, the Zika virus needs a vector (a means of transportation) to infect people. That vector is the mosquito. However, the virus has been isolated in semen and person-to-person sexual transmission has been documented. The public health impact has not yet been evaluated, and available evidence would indicate that this is an infrequent mechanism for spreading the disease.

Zika can be transmitted through blood, but this also an infrequent mechanism. The usual recommendations for safe transfusions should be followed (e.g., healthy volunteer donors).

A: There is little information on transmission from mother to baby during pregnancy or childbirth. Perinatal transmission has been reported with other vector-borne viruses, such as dengue and chikungunya. Studies are now being conducted on possible mother-to-child transmission of the virus and its possible effects on the baby. More information.

Q: What treatment exists?

A: Treatment consists of relieving pain, fever, and any other symptom that inconveniences the patient. To prevent dehydration, it is recommended to control the fever, rest, and drink plenty of water. There is no vaccine or specific drug for this virus.

Q: Can it cause death?

A: In this region, it is a new virus that up until now has had a very limited geographical and demographic distribution, and there is no evidence that it can cause death. However, sporadic cases have been reported of more serious manifestations and complications in patients with preexisting diseases or conditions, causing death.

Q: Who is at risk of Zika infection?

A: Anyone not previously exposed to the virus and who lives in an area where the mosquito is present, and where imported or local cases have been reported, may be infected. Since the Aedes mosquito is found throughout the Region (except in continental Chile and Canada), it is likely that outbreaks will occur in other countries that have not yet reported any cases.

Q: How is Zika diagnosed?

A: In most people, diagnosis is based on clinical symptoms and epidemiological circumstances (such as Zika outbreak in the patient’s area or trips to areas where the virus is circulating). Blood tests can help to confirm the diagnosis. Some virological PCR tests are useful in the first 3 to 5 days after the onset of symptoms, while others (serological tests) detect the presence of antibodies but are useful only after five days. Once it has been demonstrated that the virus is present in a given area or territory, confirmation of all cases is not necessary, and laboratory testing will be adjusted to routine virological surveillance of the disease.

Q: What is the difference between Zika, dengue and chikungunya?

A: All these diseases present similar symptoms, but certain symptoms suggest one disease or another. Dengue usually presents with higher fever and more severe muscle pain. There can be complications when the fever breaks: attention should be paid to warning signs such as bleeding. Chikungunya presents with higher fever and more intense joint pain, affecting the hands, feet, knees, and back. It can disable people, bending them over so that they cannot walk or perform simple actions such as opening a water bottle.

Q: Is there a relationship between Guillain-Barré syndrome and Zika virus?

A: An increase in Guillain-Barré syndrome (GBS) has been observed in areas where a Zika virus epidemic has been documented (e.g., in French Polynesia and Brazil).

However, a direct causal relationship has not been established between Zika virus infection and GBS. Prior infection with dengue or genetic factors could contribute to or increase cases of GBS. Several studies are underway to better establish the relationship between Zika and GBS.

GBS occurs when a person’s immune system attacks itself, in particular affecting the cells of the nervous system. This process can be initiated by infection with various viruses or bacteria. The main symptoms include muscular weakness and tingling (paresthesia) in the arms and legs, and severe complications can occur if the respiratory muscles are affected. The most seriously ill patients need attention in intensive care units.

Q: What measures should be taken to prevent Zika virus infection?

A: Prevention involves reducing mosquito populations and avoiding bites, which occur mainly during the day. Eliminating and controlling Aedes aegypti mosquito breeding sites reduces the chances that Zika, chikungunya, and dengue will be transmitted. An integrated response is required, involving action in several areas, including health, education, and the environment.

To eliminate and control the mosquito, it is recommended to:

Avoid allowing standing water in outdoor containers (flower pots, bottles, and
containers that collect water) so that they do not become mosquito breeding
sites.

Cover domestic water tanks so that mosquitoes cannot get in.

Avoid accumulating garbage: Put it in closed plastic bags and keep it in closed containers.

Unblock drains that could accumulate standing water.

Use screens and mosquito nets in windows and doors to reduce contact between mosquitoes and people.

Q: What is PAHO/WHO’s response in the Americas?

A: PAHO/WHO is working actively with the countries of the Americas to develop or maintain their ability to detect and confirm cases of Zika virus infection, treat people affected by the disease, and implement effective strategies to reduce the presence of the mosquito and minimize the likelihood of an outbreak. PAHO/WHO’s support involves:

Building the capacity of laboratories to detect the virus in a timely fashion

Advising on risk communication to respond to the introduction of the virus in the country.

Controlling the vector by working actively with the populace to eliminate mosquito populations.

Preparing recommendations for the clinical care and monitoring of persons with Zika virus infection, in collaboration with professional associations and experts from the countries.

Monitoring the geographic expansion of the virus and the emergence of complications and serious cases through surveillance of events and country reporting through the International Health Regulations channel.

Supporting health ministry initiatives aimed at learning more about the characteristics of the virus and its impact on health

Countries that have past or current evidence of Zika virus transmission. Courtesy of the CDC